Evaluation of long-term urban transitions in a megacity's building sector based on alternative socioeconomic pathways

Climate change has been one of the central issues for long-term transformations of cities. However, environmental loads have not been effectively taken into account for future urban plans. Specifically, possible reductions of carbon emissions from cities significantly rely on technological progress and human lifestyle changes, among other factors, which may be a barrier to estimating future environmental loads for cities. There is, therefore, urgent need for developing methods to integrate climate change policies with urban sustainable development planning. This research attempts to estimate future carbon emissions in the building sector in the megacity of Tokyo, considering the social and urban form transitions. The alternative socioeconomic pathways on an urban scale have been developed by the authors. The development of quantitative analysis methods linked with socioeconomic scenario assumptions and finding relevant parameters, also required novel thinking. In this research, influential explanatory variables for building stock changes are investigated and applied for the scenario analysis. Final results show two alternative 'sustainability' pathways that can reduce carbon emissions by approximately 15 percent compared to the Business As Usual scenario in 2050. This result encourages the development of various innovative sustainable pathways that are the most suitable for each city.